CI/CD requirements for monolithic applications

Monolithic applications remain a core architectural choice for many engineering teams, especially in enterprise environments, legacy systems, and high-performance applications. Unlike microservices, where individual components can be deployed independently, monolithic applications require a single, unified deployment pipeline—which brings unique challenges for CI/CD.

A well-optimized CI/CD pipeline is essential for monolithic architectures to ensure fast feedback loops, reliable deployments, and efficient scaling as the codebase grows. Without the right CI/CD tools and strategies, teams face longer build times, complex testing, and higher deployment risks.

What is a monolithic application?

A monolithic application is a single, unified software system where all components—frontend, backend, business logic, and database interactions—are tightly integrated and deployed as a single unit. Unlike microservices, where different services can be updated and scaled independently, a monolith must be built, tested, and deployed as a whole.

This architecture is common in legacy applications, enterprise software, and performance-intensive systems where strong consistency and tight coupling are necessary. While monolithic applications can be easier to develop initially, they present unique challenges as they scale—especially in terms of build times, testing complexity, and deployment risk.

The challenges of CI/CD for monolithic applications

Monolithic applications introduce unique CI/CD bottlenecks that must be addressed to maintain velocity and stability throughout the software development lifecycle:

• Slow feedback cycles – Large monolithic applications take longer to build and test, making it difficult for developers to get fast feedback on changes.
• Long build and test times – A small change often requires rebuilding and retesting the entire application, significantly increasing CI/CD runtime.
• Complex dependency management – With many interconnected modules and libraries, managing dependencies efficiently is crucial to prevent conflicts and ensure reproducible builds.
• Risky database migrations – Since monoliths typically share a single database, schema changes can break production if not carefully managed.
• High deployment risk – A failed release impacts the entire application, making rollbacks more difficult than in microservices-based architectures.
• Challenging rollback strategies – Because everything is deployed together, reverting a change requires restoring the entire system to a previous state.
• Limited scalability and resource-heavy pipelines – CI/CD pipelines for monolithic applications demand more compute power and require efficient caching and parallel execution to keep costs under control.
• Lack of visibility into performance bottlenecks – Without real-time monitoring and logging, identifying slow builds, inefficient test execution, or problematic deployments is difficult.

Best practices for CI/CD with monolithic applications

A strong CI/CD pipeline for monolithic applications should focus on speed, efficiency, and reliability. Key best practices include:

1. Automate and optimize testing early

Since monolithic applications are tightly coupled and depend on shared state, thorough testing is even more critical to catch regressions early.

• Prioritize unit tests on critical code paths – Since a small bug can impact the entire system, focus on the most-used parts of the application.
• Use integration tests for core components – Monolithic apps don’t rely on lightweight service contracts like microservices, so integration tests must be comprehensive.
• Optimize database-dependent tests – Monoliths frequently require database interaction; use transaction rollbacks or in-memory databases to speed up test execution.

2. Optimize builds with caching and parallel execution

Monoliths have larger, more complex build dependencies, making efficient build strategies essential.

• Cache compiled artifacts & dependencies – Avoid rebuilding unchanged modules to speed up CI/CD.
• Use incremental compilation – Many monolithic languages (e.g., Java, C++) support partial recompilation instead of full builds.
• Reduce dependency resolution time – Instead of resolving all dependencies every build, use dependency and artifact caching for faster execution.

3. Implement database migration strategies

Since monolithic applications often share a single database, schema changes must be carefully managed to avoid breaking deployments.

• Use zero-downtime schema migration techniques – Avoid destructive changes like DROP COLUMN in favor of “expand and contract” patterns.
• Sync database changes with application updates – Use feature flags to make new schema changes backward-compatible before switching over.
• Test migrations with real production-like data – Monolithic applications often rely on complex, relational data models that need rigorous testing before production updates.

4. Use feature flags & progressive delivery instead of risky full deployments

Since monolithic applications can’t be updated in small, isolated pieces, feature flags are essential for deploying safely without breaking production.

• Use feature flags to enable new functionality gradually – This allows teams to ship code without activating it immediately, reducing the risk of full-system failures.
• Combine feature flags with staged rollouts – If your infrastructure supports traffic splitting, use it to expose new functionality to a limited number of users first.
• Leverage blue-green deployments for critical updates – Monolithic applications don’t allow partial rollouts, so a full production swap between stable & new environments is often required.

5. Deploy confidently with built-in approval workflows

Since a monolithic release affects the entire system, adding approval workflows provides an extra layer of safety before pushing to production.

• Use approval gates for production deployments – CI/CD can require manual approval for high-risk releases.
• Add security and compliance checks before releases – Monolithic applications in regulated industries may need additional sign-offs before going live.
• Automate rollback approvals – When failures happen, having pre-approved rollback workflows speeds up recovery time.

6. Improve observability with centralized monitoring

Monolithic applications generate large volumes of logs and performance data, making centralized monitoring essential.

• Aggregate logs from all application layers – Since monolithic failures affect multiple components, full visibility is critical.
• Use database query performance monitoring – Many monolithic slowdowns come from inefficient database queries; tools like Datadog or New Relic can help identify slow queries.
• Set up anomaly detection & alerting – Instead of relying on static thresholds, use machine learning-based monitoring to detect real performance degradation.

7. Establish reliable rollback strategies

Rolling back in a monolith is far more complicated than in microservices, since everything is deployed as a single unit.

• Keep previous stable versions readily available – Instead of patching failures, it’s often safer to rollback to a known stable release.
• Use database snapshots for fast rollback – Since monoliths heavily rely on databases, having pre-snapshot rollbacks can prevent schema mismatches.
• Ensure backwards compatibility for rollback safety – Before rolling out a schema change, ensure older versions of the app can still function in case a rollback is required.

CircleCI is the best CI/CD platform for monolithic applications

Monolithic applications require powerful, efficient, and flexible CI/CD infrastructure to handle large codebases, long test cycles, and complex deployments. CircleCI provides enterprise-grade performance, scalability, and cost efficiency, making it the best platform for monolithic application development.

With CircleCI, teams building monolithic applications can:

• Run resource-intensive builds with optimized compute. Choose from Linux, Windows, macOS, Arm, and GPU runners to match your application’s needs.
• Reduce build times with caching and parallel execution. Intelligent test splitting and dependency caching ensure fast feedback cycles and efficient resource utilization.
• Deploy confidently with built-in approval workflows. Manual approval steps ensure high-risk deployments only go live after validation, reducing release failures.
• Scale CI/CD efficiently with usage-based pricing. Avoid overpaying for underutilized resources by paying only for the compute power used.
• Get full visibility into performance bottlenecks. CircleCI’s real-time insights help teams identify inefficiencies and optimize pipeline performance.
• Integrate with monitoring and database migration tools. Connect CircleCI to Datadog, New Relic, Flyway, Liquibase, and any other tool in your stack to ensure smooth deployments and real-time observability.

For monolithic applications, a lackluster CI/CD solution tacked onto an all-in-one platform isn’t enough — you need a high-performance, flexible pipeline designed for large builds, complex dependencies, and enterprise-level deployments. CircleCI delivers the best CI/CD experience for teams that take software delivery seriously.

Build and ship monolithic applications with confidence

A well-optimized CI/CD pipeline eliminates inefficiencies, speeds up development, and reduces deployment risks — even for large, complex monolithic applications. With CircleCI, teams can run faster builds, automate testing, and deploy reliably—without delays or unnecessary overhead.

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